Although epidural clonidine has been used with success in different surgical settings, there are no published studies comparing epidural combinations of bupivacaine and clonidine with bupivacaine and fentanyl (or all 3 drugs together) in patients undergoing abdominal surgery. There is now good evidence from animal and human studies to suggest that a combination of fentanyl and clonidine has more pain−relieving effect than either of the two drugs administered on its own.